1
|
Steiner P, Arlt E, Boekhoff I, Gudermann T, Zierler S. TPC Functions in the Immune System. Handb Exp Pharmacol 2023; 278:71-92. [PMID: 36639434 DOI: 10.1007/164_2022_634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Two-pore channels (TPCs) are novel intracellular cation channels, which play a key role in numerous (patho-)physiological and immunological processes. In this chapter, we focus on their function in immune cells and immune reactions. Therefore, we first give an overview of the cellular immune response and the partaking immune cells. Second, we concentrate on ion channels which in the past have been shown to play an important role in the regulation of immune cells. The main focus is then directed to TPCs, which are primarily located in the membranes of acidic organelles, such as lysosomes or endolysosomes but also certain other vesicles. They regulate Ca2+ homeostasis and thus Ca2+ signaling in immune cells. Due to this important functional role, TPCs are enjoying increasing attention within the field of immunology in the last few decades but are also becoming more pertinent as pharmacological targets for the treatment of pro-inflammatory diseases such as allergic hypersensitivity. However, to uncover the precise molecular mechanism of TPCs in immune cell responses, further molecular, genetic, and ultrastructural investigations on TPCs are necessary, which then may pave the way to develop novel therapeutic strategies to treat diseases such as anaphylaxis more specifically.
Collapse
Affiliation(s)
- Philip Steiner
- Institute of Pharmacology, Faculty of Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Elisabeth Arlt
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ingrid Boekhoff
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Susanna Zierler
- Institute of Pharmacology, Faculty of Medicine, Johannes Kepler University Linz, Linz, Austria.
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
| |
Collapse
|
2
|
Rice KL, Webb SE, Miller AL. Localized TPC1-mediated Ca2+ release from endolysosomes contributes to myoseptal junction development in zebrafish. J Cell Sci 2022; 135:jcs259564. [PMID: 35393618 DOI: 10.1242/jcs.259564] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/30/2022] [Indexed: 11/20/2022] Open
Abstract
In the trunk of developing zebrafish embryos, adjacent myotome blocks transmit contractile force via myoseptal junctions (MJs), which are dynamic structures that connect the actin cytoskeleton of skeletal muscle cells to extracellular matrix components via transmembrane protein complexes in the sarcolemma. Here, we report that the endolysosomal ion channel, two-pore channel type 1 (TPC1, encoded by tpcn1), generates highly localized non-propagating Ca2+ transients that play a distinct and required role in the capture and attachment of superficial slow skeletal muscle cells at MJs. Use of antisense morpholinos or CRISPR/Cas9 gene editing to disrupt tpcn1 gene expression resulted in abnormal MJ phenotypes, including slow skeletal muscle cells detaching from or crossing the myosepta. We also report that TPC1-decorated endolysosomes are dynamically associated with MJs in a microtubule-dependent manner, and that attenuating tpcn1 expression or TPC1 function disrupted endolysosomal trafficking and resulted in an abnormal distribution of β-dystroglycan (encoded by dag1; a key transmembrane component of the dystrophin-associated protein complex). Taken together, our data suggest that localized TPC1-generated Ca2+ signals facilitate essential endolysosomal trafficking and membrane contact events, which help form and maintain MJs following the onset of slow skeletal muscle cell contractile activity. This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Keira L Rice
- The Division of Life Science and Key State Laboratory for Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, The PRC
| | - Sarah E Webb
- The Division of Life Science and Key State Laboratory for Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, The PRC
| | - Andrew L Miller
- The Division of Life Science and Key State Laboratory for Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, The PRC
| |
Collapse
|
3
|
Halcrow PW, Kumar N, Afghah Z, Fischer JP, Khan N, Chen X, Meucci O, Geiger JD. Heterogeneity of ferrous iron-containing endolysosomes and effects of endolysosome iron on endolysosome numbers, sizes, and localization patterns. J Neurochem 2022; 161:69-83. [PMID: 35124818 PMCID: PMC9587899 DOI: 10.1111/jnc.15583] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/22/2022] [Accepted: 01/31/2022] [Indexed: 11/28/2022]
Abstract
Endolysosomes are key regulators of iron metabolism and are central to iron trafficking and redox signaling. Iron homeostasis is linked to endolysosome acidity and inhibition of endolysosome acidity triggers iron dysregulation. Because of the physiological importance and pathological relevance of ferrous iron (Fe2+ ), we determined levels of Fe2+ specifically and quantitatively in endolysosomes as well as the effects of Fe2+ on endolysosome morphology, distribution patterns, and function. The fluorescence dye FeRhoNox-1 was specific for Fe2+ and localized to endolysosomes in U87MG astrocytoma cells and primary rat cortical neurons; in U87MG cells the endolysosome concentration of Fe2+ ([Fe2+ ]el ) was 50.4 μM in control cells, 73.6 μM in ferric ammonium citrate (FAC) treated cells, and 12.4 μM in cells treated with the iron chelator deferoxamine (DFO). Under control conditions, in primary rat cortical neurons, [Fe2+ ]el was 32.7 μM. Endolysosomes containing the highest levels of Fe2+ were located perinuclearly. Treatment of cells with FAC resulted in endolysosomes that were less acidic, increased in numbers and sizes, and located further from the nucleus; opposite effects were observed for treatments with DFO. Thus, FeRhoNox-1 is a useful probe for the study of endolysosome Fe2+ , and much more work is needed to understand better the physiological significance and pathological relevance of endolysosomes classified according to their heterogeneous iron content Cover Image for this issue: https://doi.org/10.1111/jnc.15396.
Collapse
Affiliation(s)
- Peter W. Halcrow
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Nirmal Kumar
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Zahra Afghah
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Jalyn P. Fischer
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Nabab Khan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Olimpia Meucci
- Department of Physiology and Pharmacology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Jonathan D. Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| |
Collapse
|
4
|
Halcrow PW, Kumar N, Afghah Z, Fischer JP, Khan N, Chen X, Meucci O, Geiger JD. Heterogeneity of ferrous iron-containing endolysosomes and effects of endolysosome iron on endolysosome numbers, sizes, and localization patterns. J Neurochem 2022. [PMID: 35124818 DOI: 10.1111/jnc.15396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Endolysosomes are key regulators of iron metabolism and are central to iron trafficking and redox signaling. Iron homeostasis is linked to endolysosome acidity and inhibition of endolysosome acidity triggers iron dysregulation. Because of the physiological importance and pathological relevance of ferrous iron (Fe2+ ), we determined levels of Fe2+ specifically and quantitatively in endolysosomes as well as the effects of Fe2+ on endolysosome morphology, distribution patterns, and function. The fluorescence dye FeRhoNox-1 was specific for Fe2+ and localized to endolysosomes in U87MG astrocytoma cells and primary rat cortical neurons; in U87MG cells the endolysosome concentration of Fe2+ ([Fe2+ ]el ) was 50.4 μM in control cells, 73.6 μM in ferric ammonium citrate (FAC) treated cells, and 12.4 μM in cells treated with the iron chelator deferoxamine (DFO). Under control conditions, in primary rat cortical neurons, [Fe2+ ]el was 32.7 μM. Endolysosomes containing the highest levels of Fe2+ were located perinuclearly. Treatment of cells with FAC resulted in endolysosomes that were less acidic, increased in numbers and sizes, and located further from the nucleus; opposite effects were observed for treatments with DFO. Thus, FeRhoNox-1 is a useful probe for the study of endolysosome Fe2+ , and much more work is needed to understand better the physiological significance and pathological relevance of endolysosomes classified according to their heterogeneous iron content Cover Image for this issue: https://doi.org/10.1111/jnc.15396.
Collapse
Affiliation(s)
- Peter W Halcrow
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Nirmal Kumar
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Zahra Afghah
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Jalyn P Fischer
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Nabab Khan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | - Olimpia Meucci
- Department of Physiology and Pharmacology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| |
Collapse
|
5
|
Halcrow PW, Lynch ML, Geiger JD, Ohm JE. Role of endolysosome function in iron metabolism and brain carcinogenesis. Semin Cancer Biol 2021; 76:74-85. [PMID: 34139350 PMCID: PMC8627927 DOI: 10.1016/j.semcancer.2021.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023]
Abstract
Iron, the most abundant metal in human brain, is an essential microelement that regulates numerous cellular mechanisms. Some key physiological roles of iron include oxidative phosphorylation and ATP production, embryonic neuronal development, formation of iron-sulfur clusters, and the regulation of enzymes involved in DNA synthesis and repair. Because of its physiological and pathological importance, iron homeostasis must be tightly regulated by balancing its uptake, transport, and storage. Endosomes and lysosomes (endolysosomes) are acidic organelles known to contain readily releasable stores of various cations including iron and other metals. Increased levels of ferrous (Fe2+) iron can generate reactive oxygen species (ROS) via Fenton chemistry reactions and these increases can damage mitochondria and genomic DNA as well as promote carcinogenesis. Accumulation of iron in the brain has been linked with aging, diet, disease, and cerebral hemorrhage. Further, deregulation of brain iron metabolism has been implicated in carcinogenesis and may be a contributing factor to the increased incidence of brain tumors around the world. Here, we provide insight into mechanisms by which iron accumulation in endolysosomes is altered by pH and lysosome membrane permeabilization. Such events generate excess ROS resulting in mitochondrial DNA damage, fission, and dysfunction, as well as DNA oxidative damage in the nucleus; all of which promote carcinogenesis. A better understanding of the roles that endolysosome iron plays in carcinogenesis may help better inform the development of strategic therapeutic options for cancer treatment and prevention.
Collapse
Affiliation(s)
- Peter W Halcrow
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, United States
| | - Miranda L Lynch
- Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, United States
| | - Joyce E Ohm
- Department of Cancer Genetics and Genomics, Roswell Park Cancer Institute, Buffalo, NY, United States.
| |
Collapse
|
6
|
Khan N, Halcrow PW, Lakpa LK, Rehan M, Chen X, Geiger JD. Endolysosome iron restricts Tat-mediated HIV-1 LTR transactivation by increasing HIV-1 Tat oligomerization and β-catenin expression. J Neurovirol 2021; 27:755-773. [PMID: 34550543 DOI: 10.1007/s13365-021-01016-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/06/2021] [Accepted: 08/24/2021] [Indexed: 12/31/2022]
Abstract
HIV-1 transactivator of transcription (Tat) protein is required for HIV-1 replication, and it has been implicated in the pathogenesis of HIV-1-associated neurocognitive disorder (HAND). HIV-1 Tat can enter cells via receptor-mediated endocytosis where it can reside in endolysosomes; upon its escape from these acidic organelles, HIV-1 Tat can enter the cytosol and nucleus where it activates the HIV-1 LTR promoter. Although it is known that HIV-1 replication is affected by the iron status of people living with HIV-1 (PLWH), very little is known about how iron affects HIV-1 Tat activation of the HIV-1 LTR promoter. Because HIV-1 proteins de-acidify endolysosomes and endolysosome de-acidification affects subcellular levels and actions of iron, we tested the hypothesis that the endolysosome pool of iron is sufficient to affect Tat-induced HIV-1 LTR transactivation. Ferric (Fe3+) and ferrous (Fe2+) iron both restricted Tat-mediated HIV-1 LTR transactivation. Chelation of endolysosome iron with deferoxamine (DFO) and 2-2 bipyridyl, but not chelation of cytosolic iron with deferiprone and deferasirox, significantly enhanced Tat-mediated HIV-1 LTR transactivation. In the presence of iron, HIV-1 Tat increasingly oligomerized and DFO prevented the oligomerization. DFO also reduced protein expression levels of the HIV-1 restriction agent beta-catenin in the cytosol and nucleus. These findings suggest that DFO increases HIV-1 LTR transactivation by increasing levels of the more active dimeric form of Tat relative to the less active oligomerized form of Tat, increasing the escape of dimeric Tat from endolysosomes, and/or reducing beta-catenin protein expression levels. Thus, intracellular iron might play a significant role in regulating HIV-1 replication, and these findings raise cautionary notes for chelation therapies in PLWH.
Collapse
Affiliation(s)
- Nabab Khan
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Peter W Halcrow
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Leo K Lakpa
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Mohd Rehan
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Xuesong Chen
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Jonathan D Geiger
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA.
| |
Collapse
|
7
|
Khan N, Kumar N, Geiger JD. Possible therapeutic targets for SARS-CoV-2 infection and COVID-19. J Allergy Infect Dis 2021; 2:75-83. [PMID: 37564275 PMCID: PMC10414779 DOI: 10.46439/allergy.2.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
SARS-CoV-2 infection causes COVID-19, which has emerged as a health emergency worldwide. SARS-CoV-2 infects cells by binding to ACE2 receptors and enters into the cytoplasm following its escape from endolysosomes. Once in the cytoplasm, the virus replicates and eventually causes various pathological conditions including acute respiratory distress syndrome (ARDS) that is caused by pro-inflammatory cytokine storms. Thus, endolysosomes and cytokine storms are important therapeutic targets to suppress SARS-CoV-2 infection and COVID-19. Here, we discuss therapeutic targets of SARS-CoV-2 infection and available drugs that could be helpful in the suppression of the SARS-CoV-2 infection and pathological condition COVID-19. The urgency of the COVID-19 pandemic precludes the development of new drugs and increased focus on drug repurposing might provide the quickest way to finding effective medicines.
Collapse
Affiliation(s)
- Nabab Khan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58203, USA
| | - Nirmal Kumar
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58203, USA
| | - Jonathan D. Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58203, USA
| |
Collapse
|
8
|
Khan N, Chen X, Geiger JD. Possible Therapeutic Use of Natural Compounds Against COVID-19. J Cell Signal 2021; 2:63-79. [PMID: 33768214 PMCID: PMC7990267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The outbreak of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has led to coronavirus disease-19 (COVID-19); a pandemic disease that has resulted in devastating social, economic, morbidity and mortality burdens. SARS-CoV-2 infects cells following receptor-mediated endocytosis and priming by cellular proteases. Following uptake, SARS-CoV-2 replicates in autophagosome-like structures in the cytosol following its escape from endolysosomes. Accordingly, the greater endolysosome pathway including autophagosomes and the mTOR sensor may be targets for therapeutic interventions against SARS-CoV-2 infection and COVID-19 pathogenesis. Naturally existing compounds (phytochemicals) through their actions on endolysosomes and mTOR signaling pathways might provide therapeutic relief against COVID-19. Here, we discuss evidence that some natural compounds through actions on the greater endolysosome system can inhibit SARS-CoV-2 infectivity and thereby might be repurposed for use against COVID-19.
Collapse
|
9
|
Žerovnik Mekuč M, Bohak C, Hudoklin S, Kim BH, Romih R, Kim MY, Marolt M. Automatic segmentation of mitochondria and endolysosomes in volumetric electron microscopy data. Comput Biol Med 2020; 119:103693. [PMID: 32339123 DOI: 10.1016/j.compbiomed.2020.103693] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/11/2020] [Accepted: 02/29/2020] [Indexed: 12/26/2022]
Abstract
Automatic segmentation of intracellular compartments is a powerful technique, which provides quantitative data about presence, spatial distribution, structure and consequently the function of cells. With the recent development of high throughput volumetric data acquisition techniques in electron microscopy (EM), manual segmentation is becoming a major bottleneck of the process. To aid the cell research, we propose a technique for automatic segmentation of mitochondria and endolysosomes obtained from urinary bladder urothelial cells by the dual beam EM technique. We present a novel publicly available volumetric EM dataset - the first of urothelial cells, evaluate several state-of-the-art segmentation methods on the new dataset and present a novel segmentation pipeline, which is based on supervised deep learning and includes mechanisms that reduce the impact of dependencies in the input data, artefacts and annotation errors. We show that our approach outperforms the compared methods on the proposed dataset.
Collapse
Affiliation(s)
- Manca Žerovnik Mekuč
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
| | - Ciril Bohak
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
| | - Samo Hudoklin
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia.
| | - Byeong Hak Kim
- School of Electronics Engineering and Research Center for Neurosurgical Robotic System, Kyungpook National University, 41566 Daegu, South Korea; Hanwha Systems Corporation, Optronics Team, 1gongdan-ro, 39376 Gumi, South Korea.
| | - Rok Romih
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia.
| | - Min Young Kim
- School of Electronics Engineering and Research Center for Neurosurgical Robotic System, Kyungpook National University, 41566 Daegu, South Korea.
| | - Matija Marolt
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
| |
Collapse
|
10
|
Afghah Z, Chen X, Geiger JD. Role of endolysosomes and inter-organellar signaling in brain disease. Neurobiol Dis 2020; 134:104670. [PMID: 31707116 PMCID: PMC7184921 DOI: 10.1016/j.nbd.2019.104670] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/14/2019] [Accepted: 11/05/2019] [Indexed: 12/29/2022] Open
Abstract
Endosomes and lysosomes (endolysosomes) are membrane bounded organelles that play a key role in cell survival and cell death. These acidic intracellular organelles are the principal sites for intracellular hydrolytic activity required for the maintenance of cellular homeostasis. Endolysosomes are involved in the degradation of plasma membrane components, extracellular macromolecules as well as intracellular macromolecules and cellular fragments. Understanding the physiological significance and pathological relevance of endolysosomes is now complicated by relatively recent findings of physical and functional interactions between endolysosomes with other intracellular organelles including endoplasmic reticulum, mitochondria, plasma membranes, and peroxisomes. Indeed, evidence clearly indicates that endolysosome dysfunction and inter-organellar signaling occurs in different neurodegenerative diseases including Alzheimer's disease (AD), HIV-1 associated neurocognitive disease (HAND), Parkinson's disease (PD) as well as various forms of brain cancer such as glioblastoma multiforme (GBM). These findings open new areas of cell biology research focusing on understanding the physiological actions and pathophysiological consequences of inter-organellar communication. Here, we will review findings of others and us that endolysosome de-acidification and dysfunction coupled with impaired inter-organellar signaling is involved in the pathogenesis of AD, HAND, PD, and GBM. A more comprehensive appreciation of cell biology and inter-organellar signaling could lead to the development of new drugs to prevent or cure these diseases.
Collapse
Affiliation(s)
- Zahra Afghah
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201, United States of America
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201, United States of America
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58201, United States of America.
| |
Collapse
|
11
|
Lakpa KL, Halcrow PW, Chen X, Geiger JD. Readily Releasable Stores of Calcium in Neuronal Endolysosomes: Physiological and Pathophysiological Relevance. Adv Exp Med Biol 2020; 1131:681-697. [PMID: 31646530 PMCID: PMC7047846 DOI: 10.1007/978-3-030-12457-1_27] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Neurons are long-lived post-mitotic cells that possess an elaborate system of endosomes and lysosomes (endolysosomes) for protein quality control. Relatively recently, endolysosomes were recognized to contain high concentrations (400-600 μM) of readily releasable calcium. The release of calcium from this acidic organelle store contributes to calcium-dependent processes of fundamental physiological importance to neurons including neurotransmitter release, membrane excitability, neurite outgrowth, synaptic remodeling, and cell viability. Pathologically, disturbances of endolysosome structure and/or function have been noted in a variety of neurodegenerative disorders including Alzheimer's disease (AD) and HIV-1 associated neurocognitive disorder (HAND). And, dysregulation of intracellular calcium has been implicated in the neuropathogenesis of these same neurological disorders. Thus, it is important to better understand mechanisms by which calcium is released from endolysosomes as well as the consequences of such release to inter-organellar signaling, physiological functions of neurons, and possible pathological consequences. In doing so, a path forward towards new therapeutic modalities might be facilitated.
Collapse
Affiliation(s)
- Koffi L Lakpa
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Peter W Halcrow
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA.
| |
Collapse
|
12
|
Jung J, Venkatachalam K. TRPML1 and RAS-driven cancers - exploring a link with great therapeutic potential. Channels (Austin) 2019; 13:374-381. [PMID: 31526156 PMCID: PMC6768051 DOI: 10.1080/19336950.2019.1666457] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/04/2019] [Accepted: 09/08/2019] [Indexed: 12/05/2022] Open
Abstract
Activating mutations in the RAS family of proto-oncogenes represent some of the leading causes of cancer. Unmitigated proliferation of cells harboring oncogenic RAS mutations is accompanied by a massive increase in cellular bioenergetic demands, which offers unique opportunities for therapeutic intervention. To withstand the steep requirements for metabolic intermediates, RAS-driven cancer cells enhance endolysosome and autophagosome biogenesis. By degrading cellular macromolecules into metabolites that can be used by biosynthetic pathways, endolysosomes permit continued proliferation and survival in otherwise detrimental conditions. We recently showed that human cancers with activating mutations in HRAS elevate the expression of MCOLN1, which encodes an endolysosomal cation channel called TRPML1. Increased TRPML1 activity in HRAS-driven cancer cells is needed for the restoration of plasma membrane cholesterol that gets collaterally internalized during endocytosis. Inhibition of TRPML1 or knockdown of MCOLN1 leads to mislocalization of cholesterol from the plasma membrane to endolysosomes, loss of oncogenic HRAS from the cell surface, and attenuation of downstream signaling. Here, we discuss the implications of our findings and suggest strategies to leverage pathways that impinge upon TRPML1 as novel anti-cancer treatments.
Collapse
Affiliation(s)
- Jewon Jung
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Sciences Center (UTHealth), Houston, TX, USA
| | - Kartik Venkatachalam
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Sciences Center (UTHealth), Houston, TX, USA
- Graduate Program in Biochemistry and Cell Biology, MD Anderson Cancer Center and UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| |
Collapse
|
13
|
Halcrow PW, Khan N, Datta G, Ohm JE, Chen X, Geiger JD. Importance of measuring endolysosome, cytosolic, and extracellular pH in understanding the pathogenesis of and possible treatments for glioblastoma multiforme. Cancer Rep (Hoboken) 2019; 2:e1193. [PMID: 31989117 PMCID: PMC6983952 DOI: 10.1002/cnr2.1193] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Glioblastoma multiforme (GBM) is a very aggressive form of brain cancer that carries with it a tragically poor prognosis. As with many other forms of cancer, the extracellular environment near GBM tumors is acidified and is relevant to the pathogenesis of GBM because decreased pH promotes tumor cell invasion, increases angiogenesis, decreases immune surveillance, and increases resistance to possible treatments. Recently, vacuolar ATPase (v-ATPase), a proton pump that helps maintain the acidic environment in endosomes and lysosomes (hereafter referred to endolysosomes) as well as proton gradients across the plasma membrane, was identified as a novel therapeutic target for GBM. However, information is lacking about cancer cell and tissue pH of endolysosomes, cytosol and extracellular fluid. AIM Here, we measured endolysosome, cytosolic, and extracellular pH in U87MG cells in the absence and presence of the v-ATPase inhibitor bafilomycin A1. METHODS In vitro measurements of U87MG cells were conducted using LysoSensor dye and a Lysosome-RFP dye for lysosome pH, BCECF-AM for cytosolic pH, and a pH-sensitive microprobe for extracellular pH. RESULTS Bafilomycin A1 increased endolysosome pH from 5.28 to 5.57, decreased cytosolic pH from 7.01 to 6.46, and increased extracellular pH from 7.18 to 7.40. CONCLUSIONS Here, we report the ability to make pH measurements in U87MG glioblastoma cells and discuss these results in the context of GBM pathogenesis and possible treatment. This might be of some importance in understanding the pathogenesis of GBM because the highly regulated stores of hydrogen (H+) ions in endolysosomes can influence cytosolic and extracellular pH as well as the distribution, numbers, and sizes of endolysosomes.
Collapse
Affiliation(s)
- Peter W. Halcrow
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth Dakota
| | - Nabab Khan
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth Dakota
| | - Gaurav Datta
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth Dakota
| | - Joyce E. Ohm
- Department of Cancer Genetics and GenomicsRoswell Park Comprehensive Cancer CenterBuffaloNew York
| | - Xuesong Chen
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth Dakota
| | - Jonathan D. Geiger
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth Dakota
| |
Collapse
|
14
|
Khan N, Haughey NJ, Nath A, Geiger JD. Involvement of organelles and inter-organellar signaling in the pathogenesis of HIV-1 associated neurocognitive disorder and Alzheimer's disease. Brain Res 2019; 1722:146389. [PMID: 31425679 DOI: 10.1016/j.brainres.2019.146389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/26/2019] [Accepted: 08/13/2019] [Indexed: 12/30/2022]
Abstract
Endolysosomes, mitochondria, peroxisomes, endoplasmic reticulum, and plasma membranes are now known to physically and functionally interact with each other. Such findings of inter-organellar signaling and communication has led to a resurgent interest in cell biology and an increased appreciation for the physiological actions and pathological consequences of the dynamic physical and chemical communications occurring between intracellular organelles. Others and we have shown that HIV-1 proteins implicated in the pathogenesis of neuroHIV and that Alzheimer's disease both affects the structure and function of intracellular organelles. Intracellular organelles are highly mobile, and their intracellular distribution almost certainly affects their ability to interact with other organelles and to regulate such important physiological functions as endolysosome acidification, cell motility, and nutrient homeostasis. Indeed, compounds that acidify endolysosomes cause endolysosomes to exhibit a mainly perinuclear pattern while compounds that de-acidify endolysosomes cause these organelles to exhibit a larger profile as well as movement towards plasma membranes. Endolysosome pH might be an early event in the pathogenesis of neuroHIV and Alzheimer's disease and in terms of organellar biology endolysosome changes might be upstream of HIV-1 protein-induced changes to other organelles. Thus, inter-organellar signaling mechanisms might be involved in the pathogenesis of neuroHIV and other neurological disorders, and a better understanding of inter-organellar signaling might lead to improved therapeutic strategies.
Collapse
Affiliation(s)
- Nabab Khan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, United States
| | - Norman J Haughey
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Avindra Nath
- National Institute of Neurological Diseases and Stroke, Bethesda, MD, United States
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, United States.
| |
Collapse
|
15
|
Genevini P, Colombo MN, Venditti R, Marcuzzo S, Colombo SF, Bernasconi P, De Matteis MA, Borgese N, Navone F. VAPB depletion alters neuritogenesis and phosphoinositide balance in motoneuron-like cells: relevance to VAPB-linked amyotrophic lateral sclerosis. J Cell Sci 2019; 132:jcs.220061. [PMID: 30745341 DOI: 10.1242/jcs.220061] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 02/01/2019] [Indexed: 12/12/2022] Open
Abstract
VAPB and VAPA are ubiquitously expressed endoplasmic reticulum membrane proteins that play key roles in lipid exchange at membrane contact sites. A mutant, aggregation-prone, form of VAPB (P56S) is linked to a dominantly inherited form of amyotrophic lateral sclerosis; however, it has been unclear whether its pathogenicity is due to toxic gain of function, to negative dominance, or simply to insufficient levels of the wild-type protein produced from a single allele (haploinsufficiency). To investigate whether reduced levels of functional VAPB, independently from the presence of the mutant form, affect the physiology of mammalian motoneuron-like cells, we generated NSC34 clones, from which VAPB was partially or nearly completely depleted. VAPA levels, determined to be over fourfold higher than those of VAPB in untransfected cells, were unaffected. Nonetheless, cells with even partially depleted VAPB showed an increase in Golgi- and acidic vesicle-localized phosphatidylinositol-4-phosphate (PI4P) and reduced neurite extension when induced to differentiate. Conversely, the PI4 kinase inhibitors PIK93 and IN-10 increased neurite elongation. Thus, for long-term survival, motoneurons might require the full dose of functional VAPB, which may have unique function(s) that VAPA cannot perform.
Collapse
Affiliation(s)
- Paola Genevini
- Consiglio Nazionale delle Ricerche Neuroscience Institute and BIOMETRA Department, Università degli Studi di Milano, Milan 20129, Italy
| | - Maria Nicol Colombo
- Consiglio Nazionale delle Ricerche Neuroscience Institute and BIOMETRA Department, Università degli Studi di Milano, Milan 20129, Italy
| | | | - Stefania Marcuzzo
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico 'Carlo Besta', Milan 20133, Italy
| | - Sara Francesca Colombo
- Consiglio Nazionale delle Ricerche Neuroscience Institute and BIOMETRA Department, Università degli Studi di Milano, Milan 20129, Italy
| | - Pia Bernasconi
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico 'Carlo Besta', Milan 20133, Italy
| | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Pozzuoli 80078, Italy.,Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples 80133, Italy
| | - Nica Borgese
- Consiglio Nazionale delle Ricerche Neuroscience Institute and BIOMETRA Department, Università degli Studi di Milano, Milan 20129, Italy
| | - Francesca Navone
- Consiglio Nazionale delle Ricerche Neuroscience Institute and BIOMETRA Department, Università degli Studi di Milano, Milan 20129, Italy
| |
Collapse
|
16
|
Lam SM, Wang R, Miao H, Li B, Shui G. An integrated method for direct interrogation of sphingolipid homeostasis in the heart and brain tissues of mice through postnatal development up to reproductive senescence. Anal Chim Acta 2018; 1037:152-158. [PMID: 30292289 DOI: 10.1016/j.aca.2018.01.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 12/30/2017] [Accepted: 01/08/2018] [Indexed: 11/18/2022]
Abstract
Development of rapid metabolomic methods poised for pathway discovery is expected to facilitate the identification of therapeutic candidates in the metabolomic approach to translational medicine. Using sphingolipid homeostasis as a prototype, we present herein an integrated method to facilitate a fast interrogation of altered sphingolipid (and phospholipid) metabolism associated with perturbed endolysosomal functions in mammalian systems. Constructed upon high performance liquid chromatography coupled to mass spectrometry, this method allows semi-quantitative measurements of more than 300 individual species within 20 min. The method was applied to investigate cardiac- and neural-specific developmental changes in sphingolipid regulation from the postnatal stage to reproductive senescence in mice, revealing that endogenous lysobisphosphatidic acids and specific complex glycosphingolipids are tightly co-regulated to foster concerted reductions in sphingolipid levels at distinct stages of postnatal development. Our lipidomic data suggest that such changing regulatory patterns in sphingolipid homeostasis is attributed to differential endolysosomal degradation of complex sphingolipids, which may be critical in ensuring efficient sphingolipid catabolism and organismal health at each stage of postnatal development.
Collapse
Affiliation(s)
- Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
| | - Raoxu Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Huan Miao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Bowen Li
- Lipidall Technologies Company Limited, Changzhou 213022, Jiangsu Province, People's Republic of China
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; University of Chinese Academy of Sciences, Beijing, People's Republic of China.
| |
Collapse
|
17
|
Soliman ML, Geiger JD, Chen X. Caffeine Blocks HIV-1 Tat-Induced Amyloid Beta Production and Tau Phosphorylation. J Neuroimmune Pharmacol 2016; 12:163-170. [PMID: 27629410 DOI: 10.1007/s11481-016-9707-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/02/2016] [Indexed: 12/31/2022]
Abstract
The increased life expectancy of people living with HIV-1 who are taking effective anti-retroviral therapeutics is now accompanied by increased Alzheimer's disease (AD)-like neurocognitive problems and neuropathological features such as increased levels of amyloid beta (Aβ) and phosphorylated tau proteins. Others and we have shown that HIV-1 Tat promotes the development of AD-like pathology. Indeed, HIV-1 Tat once endocytosed into neurons can alter morphological features and functions of endolysosomes as well as increase Aβ generation. Caffeine has been shown to have protective actions against AD and based on our recent findings that caffeine can inhibit endocytosis in neurons and can prevent neuronal Aβ generation, we tested the hypothesis that caffeine blocks HIV-1 Tat-induced Aβ generation and tau phosphorylation. In SH-SY5Y cells over-expressing wild-type amyloid beta precursor protein (AβPP), we demonstrated that HIV-1 Tat significantly increased secreted levels and intracellular levels of Aβ as well as cellular protein levels of phosphorylated tau. Caffeine significantly decreased levels of secreted and cellular levels of Aβ, and significantly blocked HIV-1 Tat-induced increases in secreted and cellular levels of Aβ. Caffeine also blocked HIV-1 Tat-induced increases in cellular levels of phosphorylated tau. Furthermore, caffeine blocked HIV-1 Tat-induced endolysosome dysfunction as indicated by decreased protein levels of vacuolar-ATPase and increased protein levels of cathepsin D. These results further implicate endolysosome dysfunction in the pathogenesis of AD and HAND, and by virtue of its ability to prevent and/or block neuropathological features associated with AD and HAND caffeine might find use as an effective adjunctive therapeutic agent.
Collapse
Affiliation(s)
- Mahmoud L Soliman
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, 504 Hamline St., Grand Forks, ND, 58203, USA
| | - Jonathan D Geiger
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, 504 Hamline St., Grand Forks, ND, 58203, USA.
| | - Xuesong Chen
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, 504 Hamline St., Grand Forks, ND, 58203, USA
| |
Collapse
|
18
|
Hui L, Geiger NH, Bloor-Young D, Churchill GC, Geiger JD, Chen X. Release of calcium from endolysosomes increases calcium influx through N-type calcium channels: Evidence for acidic store-operated calcium entry in neurons. Cell Calcium 2015; 58:617-27. [PMID: 26475051 DOI: 10.1016/j.ceca.2015.10.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/02/2015] [Accepted: 10/04/2015] [Indexed: 01/22/2023]
Abstract
Neurons possess an elaborate system of endolysosomes. Recently, endolysosomes were found to have readily releasable stores of intracellular calcium; however, relatively little is known about how such 'acidic calcium stores' affect calcium signaling in neurons. Here we demonstrated in primary cultured neurons that calcium released from acidic calcium stores triggered calcium influx across the plasma membrane, a phenomenon we have termed "acidic store-operated calcium entry (aSOCE)". aSOCE was functionally distinct from store-operated calcium release and calcium entry involving endoplasmic reticulum. aSOCE appeared to be governed by N-type calcium channels (NTCCs) because aSOCE was attenuated significantly by selectively blocking NTCCs or by siRNA knockdown of NTCCs. Furthermore, we demonstrated that NTCCs co-immunoprecipitated with the lysosome associated membrane protein 1 (LAMP1), and that aSOCE is accompanied by increased cell-surface expression levels of NTCC and LAMP1 proteins. Moreover, we demonstrated that siRNA knockdown of LAMP1 or Rab27a, both of which are key proteins involved in lysosome exocytosis, attenuated significantly aSOCE. Taken together our data suggest that aSOCE occurs in neurons, that aSOCE plays an important role in regulating the levels and actions of intraneuronal calcium, and that aSOCE is regulated at least in part by exocytotic insertion of N-type calcium channels into plasma membranes through LAMP1-dependent lysosome exocytosis.
Collapse
Affiliation(s)
- Liang Hui
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58203, USA
| | - Nicholas H Geiger
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58203, USA
| | - Duncan Bloor-Young
- Department of Pharmacology, University of Oxford, Mansfield Rd., Oxford OX1 3QT, UK
| | - Grant C Churchill
- Department of Pharmacology, University of Oxford, Mansfield Rd., Oxford OX1 3QT, UK
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58203, USA.
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58203, USA
| |
Collapse
|